The present invention relates to catalysts for the homogenous hydrogenation or hydrosilylation of carbonyl compounds. More specifically, the invention relates to processes for the hydrogenation of ketones and aldehydes using organometallic complexes of tungsten (W) and molybdenum (Mo) as catalysts or catalyst precursors. The invention also relates to processes for the hydrosilylation of ketones, aldehydes and esters using the same catalysts or catalyst precursors.
Hydrogenation reactions involve the addition of hydrogen to an organic compound whereby, for example, a ketone can be reduced to an alcohol. Prior art processes have generally required the presence of a heterogeneous catalyst with a solid phase of platinum, rhodium, palladium or nickel along with relatively high hydrogen pressure and elevated temperature.
Other hydrogenation processes currently in use employ inexpensive Mo and W metals to hydrogenate ketones under mild conditions of temperature and pressure. However, a limitation encountered with these processes is the decomposition of the catalysts, due to dissociation of a phosphine ligand.
Hydrosilylation reactions involve the addition of hydrosilane to ketones, aldehydes, or esters to form primarily alkoxysilanes. Prior art hydrosilylation processes have also required rhodium, platinum or palladium complexes as catalysts.
Thus, traditional homogeneous catalysts for hydrogenation or hydrosilylation of ketones or aldehydes use precious metals such as platinum (Pt), rhodium (Rh), iridium (Ir) or ruthenium (Ru), which are expensive and, therefore, frequently uneconomical. In contrast, the catalysts of the present invention, which use either molybdenum (Mo) or tungsten (W), are prepared with less expensive metals, and, therefore, offer economic advantages.
The present invention relates to catalysts and processes that use the catalysts for the homogeneous catalytic hydrogenation of ketones and aldehydes to alcohols with H2 as the stoichiometric redundant and organometallic tungsten (W) and molybdenum (Mo) complexes as the catalysts.
The present invention also relates to catalysts and processes for the hydrosilylation of ketones, aldehydes or esters, represented by the formulas R(Cxe2x95x90O)R1, R(Cxe2x95x90O)H or R(CO2)R1. The functional groups R and R1 are selected from hydrogen, C1-30 hydrocarbyl radicals and substituted-hydrocarbyl radicals, which can be the same or different.
The catalyst or catalyst precursor includes an organometallic complex represented by the formula I
[CpM(CO)2(NHC)Lk]+Axe2x88x92xe2x80x83xe2x80x83I
wherein M is a molybdenum or tungsten atom; Cp is substituted or unsubstituted cyclopentadienyl radical represented by the formula [C5Q1Q2Q3Q4Q5], wherein Q1 to Q5 are independently selected from the group consisting of H radicals, hydrocarbyl radicals and substituted hydrocarbyl radicals, halogens (F, Cl, Br, I), halogen-substituted hydrocarbyl radicals, and radicals represented by the formulas xe2x80x94ORxe2x80x2, xe2x80x94C(O)Rxe2x80x2, xe2x80x94CO2Rxe2x80x2, xe2x80x94SiRxe2x80x23, xe2x80x94NRxe2x80x2Rxe2x80x3 wherein Rxe2x80x2 and Rxe2x80x3 are independently selected from the group consisting of H radicals, hydrocarbyl radicals, halogens, and halogen-substituted hydrocarbyl radicals, wherein further Q1 to Q5 radicals can be optionally linked to each other to form a stable bridging group; NHC is any N-heterocyclic carbene ligand, L is either any neutral electron donor ligand wherein k is a number from 0 to 1 or L is an anionic ligand wherein k is 2, and Axe2x88x92 is an anion.
In an embodiment, the catalysts of the invention can be prepared by reacting a metal hydride represented by the formula II:
CpM(CO)2(NHC)Hxe2x80x83xe2x80x83II
with a hydride removing agent selected from BR3 or a compound represented by formula Y+Axe2x88x92, wherein Y+ is selected from the group consisting of (aryl)3C+, (aryl)2HC+, C7H7+, R3NH+, Ag+ and (C5R5)2Fe+, wherein R is a hydrocarbyl or substituted hydrocarbyl, Axe2x88x92 is an anion selected from the group consisting of BF4xe2x88x92, PF6xe2x88x92, SbF6xe2x88x92, CF3SO3xe2x88x92, CB11H12xe2x88x92, CB9H10xe2x88x92 CB9H5X5xe2x88x92; CB11H6X6xe2x88x92; wherein X is F Cl, Br or I, HBR3xe2x88x92, wherein R is hydrocarbyl or substituted hydrocarbyl, and [(Mxe2x80x2)Z1 Z2 . . . Zn]xe2x88x92, Mxe2x80x2 is an element selected from atoms of group 13, n is the total number of Z ligands or n is 4, and Z1 to Zn are independently selected from the group consisting of H radical, C1-20 hydrocarbyl radical, substituted hydrocarbyl radical, halogens, halogen-substituted hydrocarbyl radical, hydrocarbyl-, halogen-substituted hydrocarbyl organometalloid radical, xe2x80x94OR, xe2x80x94C(O)Rxe2x80x2, xe2x80x94CO2Rxe2x80x2, and xe2x80x94NRxe2x80x2Rxe2x80x3, wherein Rxe2x80x2 and Rxe2x80x3 are independently selected from the group consisting of H radicals, C1-20 hydrocarbyl radical, halogens, and halogen-substituted hydrocarbyl radical; Z1 to Zn radicals can be optionally linked to each other to form a stable bridging group. In the metal hydride of formula II, Cp, M and NHC are as described herein above.
The process for catalytic hydrogenation includes contacting an organic compound which contains at least one reducible functional group selected from the group consisting of R(Cxe2x95x90O)R1 and R(Cxe2x95x90O)H, wherein R and R1 are each independently selected from hydrogen (H) or any C1-C20 hydrocarbyl or substituted-hydrocarbyl radical with hydrogen in the presence of a catalyst to form a reaction mixture, wherein the catalyst comprises an organometallic complex described above and represented by the formula:
[CpM(CO)2(NHC)Lk]+Axe2x88x92xe2x80x83xe2x80x83I
wherein Cp, M, NHC, Lk and Axe2x88x92 are as described hereinbelow.
The process for catalytic hydrosilylation includes contacting an organic compound which contains at least one functional group selected from the group consisting of R(Cxe2x95x90O)R1, R(Cxe2x95x90O)H, and R(CO2)R1, wherein R and R1 are each independently selected from hydrogen (H) or any C1-C30 hydrocarbyl or substituted-hydrocarbyl radical in the presence of hydrosilane with a catalyst to form a mixture, wherein the catalyst comprises an organometallic complex described above and represented by the formula:
[CpM(CO)2(NHC)Lk]+Axe2x88x92xe2x80x83xe2x80x83I
wherein Cp, M, NHC, Lk and Axe2x88x92 are as described hereinbelow.
The hydrogenation process is carried out in the presence of hydrogen at a pressure from 1 atmosphere to 5000 psi, and at a temperature of from xe2x88x9295xc2x0 C. to 120xc2x0 C. Preferably, the pressure is from about 1 atmosphere to about 800 psi and the temperature is from 20xc2x0 C. to 100xc2x0 C. The hydrosilylation process is carried out at a temperature from about xe2x88x9295xc2x0 C. to about 120xc2x0 C. and, in one aspect of the invention, from about 20xc2x0 C. to about 100xc2x0 C.
As a result of the present invention catalysts are provided with significantly higher lifetime and increased thermal stability. Moreover, the homogeneous organometallic Mo and W complexes of the present invention provide an effective hydrogenation or hydrosilylation catalyst at a considerably reduced cost over the prior art catalysts that use Pt, Rh, Ir or Ru complexes.
The present invention relates broadly to catalysts or catalyst precursors used for a variety of hydrogenation or hydrosilylation reactions.
The active catalyst of the present invention is an organometallic complex represented by the formula:
[CpM(CO)2(NHC)Lk]+Axe2x88x92xe2x80x83xe2x80x83I
wherein M is a molybdenum or tungsten atom; Cp is substituted or unsubstituted cyclopentadienyl radical represented by the formula [C5Q1Q2Q3Q4Q5], wherein Q1 to Q5 are independently selected from the group consisting of H radicals, hydrocarbyl radicals and substituted hydrocarbyl radicals, halogens (F, Cl, Br, I), halogen-substituted hydrocarbyl radicals, and radicals represented by xe2x80x94ORxe2x80x2, xe2x80x94C(O)Rxe2x80x2, xe2x80x94CO2Rxe2x80x2, xe2x80x94SiRxe2x80x23, xe2x80x94NRxe2x80x2Rxe2x80x3, wherein Rxe2x80x2 and Rxe2x80x3 are independently selected from the group consisting of H radicals, hydrocarbyl radicals, halogens, and halogen-substituted hydrocarbyl radicals), wherein Q1 to Q5 radicals can be linked to each other through a stable bridging group, NHC is any N-heterocyclic carbene ligand, L is either any neutral electron donor ligand, wherein k is a number from 0 to 1, or L is an anion ligand wherein k is 2, and Axe2x88x92 is an anion. NHC can be an unsubstituted or substituted N-heterocyclic carbene selected from the group consisting of carbenes represented by formula III 
wherein R4, R5, R6, R7, R8 and R9 are each independently hydrogen, halogen or a substituent selected from the group consisting of C1-C20 alkyl, C2-C20 alkenyl, C2-C20 alkynyl, aryl, C1-C20 carboxylate, C1-C20 alkoxy, C2-C20 alkenyloxy, C2-C20 alkynyloxy, aryloxy, C2-C20 alkoxycarbonyl, C1-C20 alkylthiol, aryl thiol, C1-C20 alkylsulfonyl and C1-C20 alkylsulfinyl. Further, each of the R4, R5, R6, R7, R8 and R9 radicals can be optionally substituted with one or more moieties selected from the group consisting of C1-C20 hydrocarbyl, C1-C20 alkoxy, and other functional groups, examples of which include but are not limited to hydroxyl, thiol, thioether, ketone, aldehyde, ester, ether, amine, imine, amide, nitro, carboxylic acid, disulfide, carbonate, isocyanate, carbodiimide, carboalkoxy, carbamate, and halogen, wherein R4, R5, R6, R7, R8 and R9 radicals are optionally linked to each other to form a stable bridging group. In the metal hydride or formula II, Cp, M and NHC are as described herein above.
The inclusion of an NHC ligand in the Mo and W catalysts of the invention has been found to improve the catalytic activity of these organometallic complexes.
In another aspect of the invention, the N-heterocyclic carbene ligand is 1,3-bis(2, 4,6-trimethylphenyl)-imidazol-2-ylidene (IMes).
When NHC is IMes the catalysts of the present invention arc represented by the following formula: 
wherein M is Mo or W.
The NHC ligands described above arc easily obtained in accordance with methods well known in the art such as are described by Herrmann et al. in xe2x80x9cN-Heterocyclic Carbenes,xe2x80x9d Angew. Chem. Int. Ed, 36, 2162-2187, (1997) and Herrmann et al. in xe2x80x9cN-Heterocyclic Carbenes: A New Concept in Organometallic Catalysts,xe2x80x9d Angew. Chem. Int. Ed., 41, 1290-1309, (2002).
In an embodiment, L can be selected from the group consisting of a hydrocarbon or halogenated hydrocarbon solvent molecule, a dihydrogen (H2) or dihydride (Hxe2x88x92)2, a ketone or aldehyde substrate, a product alcohol molecule and mixtures thereof.
In another embodiment, L can be selected from the group consisting of a hydrocarbon or halogenated hydrocarbon solvent molecule, a dihydrogen (H2) or hydrosilane, a ketone, an aldehyde or an ester substrate, an alkoxysilane, ether, or alcohol product molecule and mixtures thereof, or any combination of two anionic ligands such as hydride (Hxe2x88x92) and silyl (SiR10R11R12)xe2x88x92 and mixtures thereof, wherein R10, R11, R12 are independently hydrogen, halogen or a substituent selected from the group consisting of C1-C20 alkyl, C2-C20 alkenyl, C2-C20 alkynyl, aryl, C1-C20 carboxylate, C1-C20 alkoxy, C2-C20 alkenyloxy, C2-C20 alkynyloxy, aryloxy, C2-C20 alkoxycarbonyl, C1-C20 alkylthiol, aryl thiol, C1-C20 alkylsulfonyl and C1-C20 alkylsulfinyl, wherein further each R10, R11, R12 is optionally substituted with one or more moieties selected from the group consisting of C1-C20 hydrocarbyl, C1-C20 alkoxy, hydroxyl, thiol,thioether, ketone, aldehyde, ester, ether, amine, imine, amide, nitro, carboxylic acid, disulfide, carbonate, isocyanate, carbodiimide, carboalkoxy, carbamate and halogen.
For purposes of this invention, the term xe2x80x9chydrocarbonxe2x80x9d refers to all permissible compounds having at least one hydrogen and one carbon atom. In a broad aspect, the permissible hydrocarbons include acyclic and cyclic, branched and unbranched, carbocyclic and heterocyclic, aromatic and nonaromatic organic compounds which can be substituted or unsubstituted having C1-30 for nonaromatic organic compounds and C3-36 for aromatic organic compounds.
As used herein, the term xe2x80x9chydrocarbylxe2x80x9d refers to univalent groups formed by removing a hydrogen atom from a hydrocarbon having 1-30 carbons.
As used herein, the term xe2x80x9csubstitutedxe2x80x9d includes all permissible substituents of organic compounds unless otherwise indicated In a broad aspect, the permissible substituents include acyclic and cyclic, branched and unbranchcd, carbocyclic and heterocyclic, aromatic and nonaromatic substituents of organic compounds. Illustrative substituents include, for example, alkyl, alkyloxy, aryl, aryloxy, hydroxy, hydroxyalkyl, amino, aminoalkyl, halogen and the like in which the number of carbons can range from 1 to about 30. The permissible substituents can be one or more and the same or different for appropriate organic compounds. This invention is not intended to be limited in any manner by the permissible substituents of organic compounds.
As used herein, the term xe2x80x9carylxe2x80x9d refers to an aromatic cyclic structure containing at least one monocyclic carbon ring including without limitation phenyl, naphthyl, anthracenyl and the like. xe2x80x9cSubstituted arylxe2x80x9d refers to an aryl group substituted with substituents as defined hereinabove.
Anion (Axe2x88x92) can be selected from the group consisting of HBR3xe2x88x92, wherein R is a hydrocarbyl or substituted hydrocarbyl, BF4xe2x88x92, PF6xe2x88x92, SbF6xe2x88x92, CF3SO3xe2x88x92, CB11H12xe2x88x92, CB9H10xe2x88x92, CB9H5X5xe2x88x92, CB11H6X6xe2x88x92, wherein X is F, Cl, Br and I, and [(Mxe2x80x2)Z1 Z2 . . . xe2x80x94Zn]xe2x88x92 wherein, Mxe2x80x2 is an element selected from the atoms of group 13; n is the total number of Z ligands, and Z1 to Zn are independently selected from the group consisting of H radicals, C1-C20 hydrocarbyl radicals and substituted hydrocarbyl radicals, halogens (F, Cl, Br, I), halogen-substituted hydrocarbyl radicals, hydrocarbyl- and halogen-substituted hydrocarbyl organometalloid radicals, and radicals represented by the formulas xe2x80x94ORxe2x80x2, xe2x80x94C(O)Rxe2x80x2, xe2x80x94CO2Rxe2x80x2, xe2x80x94NRxe2x80x2Rxe2x80x3, wherein Rxe2x80x2 and Rxe2x80x3 are independently selected from the group consisting of H radicals, C1-C20 hydrocarbyl radicals, halogens, and halogen-substituted hydrocarbyl radicals; Z1 to Zn radicals can be optionally linked to each other to form a stable bridging group. In another aspect, the total number of Z ligands is four.
Mxe2x80x2 can be any metal of group 13 of the Periodic Table of Elements as published by CRC Press, Inc., 1984 including but not limited to boron, aluminum or gallium. Z1 to Zn are each fluorine substituted phenyl, naphtyl or anthracenyl radicals.
In another embodiment, the catalyst of the present invention can further include a solvent of crystallization thereby forming [CpW(CO)2 (NHC)Lk]+[A]xe2x88x92.Yxe2x80x2h, wherein h is a number from 0 to 1 and Yxe2x80x2 is selected from the group consisting of any hydrocarbon, aromatic hydrocarbon, halocarbon, or ether, examples of which include but are not limited to hexane, benzene, toluene, tetrahydrofuran, diethyl ether and mixtures thereof.
The catalysts of the present invention have novel and valuable properties. For example, a stability at room temperature (about 23xc2x0 C.) and a useful combination of solubility properties allows the use of the catalyst in xe2x80x9cneatxe2x80x9d reagents, i.e., in the absence of a solvent. Another characteristic is that whenever the substrates do not have aromatic groups, the catalysts precipitate upon completion of the hydrosilylation reaction, and can be efficiently recovered from the reaction mixtures and reused. Thus many catalysts of the present invention are recyclable.
The catalysts of the present invention are prepared by reacting a metal hydride represented by the formula CpM(CO)2(NHC)H with a hydride removing agent selected from BR3 or a compound represented by formula Y+Axe2x88x92, wherein Y+ is selected from the group consisting of (aryl)3C+, (aryl)2HC+, C7H7+, R3NH+, Ag+ and (C5R5)2Fe+, wherein R is a hydrocarbyl radical or substituted hydrocarbyl radical, Axe2x88x92 is all anion selected from the group consisting of BF4xe2x88x92, PF6xe2x88x92, SbF6xe2x88x92, CF3SO3xe2x88x92, CB11H12xe2x88x92, CB9H10xe2x88x92, CB9H5X5xe2x88x92, CB11H6X6xe2x88x92, wherein X is F, Cl, Br or I, HBR3xe2x88x92, wherein R is a hydrocarbyl radical or subsubstituted hydrocarbyl radical, and [(Mxe2x80x2)Z1 Z2 . . . Zn]xe2x88x92, Mxe2x80x2 is an element selected from atoms of group 13, n is the total number of Z ligands or n is 4, and Z1 to Zn are independently selected from the group consisting of H radical, C1-20 hydrocarbyl radical, substituted hydrocarbyl radical, halogens, halogen-substituted hydrocarbyl radical, hydrocarbyl-, halogen-substituted hydrocarbyl organometalloid radical, xe2x80x94OR, xe2x80x94C(O)Rxe2x80x2, xe2x80x94CO2Rxe2x80x2, and xe2x80x94NRxe2x80x2Rxe2x80x3, wherein Rxe2x80x2 and Rxe2x80x3 are independently selected from the group consisting of H radicals, C1-20 hydrocarbyl radical, halogens, and halogen-substituted hydrocarbyl radical; said Z1 to Zn radicals optionally linked to each other to form a stable bridging group.
In one aspect, the hydride removing agent is Ph3C+Axe2x88x92, wherein Ph is C6H5 and Axe2x88x92 is an anion as described hereinabove.
The metal hydride represented by the formula CpM(CO)2(NHC)H is prepared by reacting a metal phosphine hydride represented by the formula CpM(CO)2(PR3)H, wherein R is any C1-C20 alkyl or C6-C36 aryl group and combination thereof with NHC, which is as described herein above.
The active catalyst can be prepared prior to being mixed with the organic compound that is being hydrogenated or hydrosilylated, or it can be generated in the reaction mixture. When the catalyst is prepared in the reaction mixture, the metal hydride can be mixed with the hydride removing agent.
Method of Using the Organometallic Complexes
The organometallic complexes of the present invention can be used broadly as catalysts for hydrogenation or hydrosilylation reactions.
The present invention provides a process for hydrogenating of ketones and aldehydes to alcohols using organometallic molybdenum and tungsten complexes as catalysts. Using the process of this invention, unsaturated organic compounds can be hydrogenated to give the corresponding saturated derivatives. Organic compounds which may be hydrogenated in accordance with the present invention include but are not limited to ketones and aldehydes.
In an aspect, the organic compound that is hydrogenated can be represented by at least one reducible functional group selected from the group consisting of R1(Cxe2x95x90O)R2 and R1(Cxe2x95x90O)H, wherein R1 and R2 are each independently selected from any C1-C20 hydrocarbyl group. The hydrogenation of ketones and aldehydes involves the overall addition of two hydrogen atoms to the carbon-oxygen double bond to result in the formation of the corresponding alcohol.
The hydrogenation process of the invention includes contacting aldehydes or ketones with hydrogen in the presence of the organometallic catalyst of the invention that is represented by the formula I:
[CpM(CO)2(NHC)Lk]+Axe2x88x92xe2x80x83xe2x80x83I
wherein M is a molybdenum or tungsten atom, Cp is substituted or unsubstituted cyclopentadienyl radical represented by the formula [C5Q1Q2Q3Q4Q5], wherein Q1 to Q5 are independently selected from the group consisting of H radicals, C1-C20 hydrocarbyl radicals and substituted hydrocarbyl radicals halogens (F, Cl, Br, I), halogen-substituted hydrocarbyl radicals, and radicals represented by the formulas xe2x80x94ORxe2x80x2, xe2x80x94C(O)Rxe2x80x2, xe2x80x94CO2Rxe2x80x2, xe2x80x94SiRxe2x80x23, xe2x80x94NRxe2x80x2Rxe2x80x3, wherein Rxe2x80x2 and Rxe2x80x3 are independently selected from the group consisting of H radicals, hydrocarbyl radicals, halogens, and halogen-substituted hydrocarbyl radicals, said Q1 to Q5 radicals can optionally be linked to each other to form a stable bridging group; NHC is any N-heterocyclic carbene ligand, L is either any neutral electron donor ligand, k is a number from 0 to 1 or L is an anionic ligand, wherein k is 2, and (Axe2x88x92) is an anion as described hereinabove.
NHC can be an unsubstituted or substituted N-heterocyclic carbene as was more specifically described hereinabove. In an embodiment NHC can be IMes.
In a hydrogenation process, L can be selected from the group consisting of a hydrocarbon or halogenated hydrocarbon solvent molecule, a dihydrogen (H2) or dihydride (Hxe2x88x92)2, a ketone or aldehyde substrate, a product alcohol molecule and mixtures thereof.
Anion (Axe2x88x92) can be selected from the group consisting of BF4xe2x88x92, PF6xe2x88x92, SbF6xe2x88x92, CF3SO3xe2x88x92, CB11H12xe2x88x92, CB9H10xe2x88x92, CB9H5X5xe2x88x92, CB11H6X6xe2x88x92, wherein X is F, Cl, Br or I, HBR3xe2x88x92, wherein R is a hydrocarbyl radical or substituted hydrocarbyl radical, and [(Mxe2x80x2)Z1 Z2 . . . Zn]xe2x88x92 as was more specifically described hereinabove.
The present invention also provides a process for hydrosilylation of ketones, aldehydes and esters to alkoxysilanes, ethers or alcohols using organometallic molybdenum and tungsten complexes of the invention as the catalysts. The organic compound that can be hydrosilylated contains at least one reducible functional group selected from the group consisting of R(Cxe2x95x90O)R1, R(Cxe2x95x90O)H or R1(CO2)R2, wherein R1 and R2 are each independently selected from hydrocarbyl radicals or substituted-hydrocarbyl radicals, which can be the same or different.
The hydrosilylation process includes contacting aldehydes, ketones or esters with hydrosilanes in the presence of the organometallic catalyst of the present invention as described herein above.
In a hydrosilylation process, L can be selected from the group consisting of a hydrocarbon or halogenated hydrocarbon solvent, a dihydrogen (H2) or hydrosilane, a ketone, an aldehyde or an ester substrate, an alkoxysilane, ether, or alcohol product molecule and mixtures thereof, or any combination of two anionic ligands such as hydride (Hxe2x88x92) and silyl (SiR10R11R12)xe2x88x92, wherein R10, R11 and R12 are each independently hydrogen, halogen or a substituent selected from the group consisting of C1-C20 alkyl, C2-C20 alkenyl, C2-C20 alkynyl, aryl, C1-C20 carboxylate, C1-C20 alkoxy, C2-C20 alkenyloxy, C2-C20 alkynyloxy, aryloxy, C2-C20 alkoxycarbonyl, C1-C20 alkylthiol, aryl thiol, C1-C20 alkylsulfonyl and C1-C20 alkylsulfinyl, wherein further each R10, R11, R12 is optionally substituted with one or more moieties selected from the group consisting of C1-C20 hydrocarbyl, C1-C20 alkoxy, hydroxyl, thiol, thioether, ketone, aldehyde, ester, ether, amine, imine, amide, nitro, carboxylic acid, disulfide; carbonate, isocyanate, carbodiimide, carboalkoxy; carbamate and halogen.
Hydrosilylation of ketone is of synthetic interest because when followed by hydrolysis of the resulting alkoxysilane, this reaction provides a mild route for reducing ketones to secondary alcohols.
The hydrogenation and hydrosilylation processes of the present invention can be carried out over a wide range of temperatures and pressures. For example, the pressure of hydrogen in the hydrogenation reactions can vary over a range from about 1 atmosphere to about 5,000 psi, the temperature can vary over a range from xe2x88x9295xc2x0 C. to about 120xc2x0 C. Nevertheless, the processes of the present invention can be conducted under mild conditions of temperatures and pressures including without limitations 1 atmosphere and room temperature of about 23xc2x0 C. In certain embodiments the pressure can range from about 1 atmosphere to about 800 psi and the temperature from about 20xc2x0 C. to about 100xc2x0 C. The temperature range for hydrosilylation reactions is from about xe2x88x9295xc2x0 C. to about 120xc2x0 C. and, in another aspect of the invention, from about 20xc2x0 C. to about 100xc2x0 C.
Various solvents may be used with the inventive methods of hydrogenation or hydrosilylation.
Any solvent which is chemically inert, which does not interfere with the hydrogenation or hydrosilylation reaction and which at least partially dissolves the catalyst may be employed. The solvents can be aromatics such as toluene, xylene, mesitylene and benzene or halogenated aromatics and other well known solvents such as hexane, tetrahydrofuran and diethyl ether. If the reactants are mutually soluble, the use of a solvent is not necessary and the catalysts can catalyze the reaction in the absence of a solvent as xe2x80x9cneatxe2x80x9d reagents. In addition, the substrate, either a ketone, aldehyde or ester, can be partially soluble or it can be completely soluble in the solvent.
The active catalyst can be prepared prior to being mixed with the organic compound that is being hydrogenated or hydrosilylated and it can also be generated in the reaction mixture. When the catalyst is prepared in the reaction mixture, the metal hydride is mixed with hydride removing agent as described hereinabove.
The processes of the invention can be conducted in any type of apparatus that enables intimate contact of the reactants and control of operating conditions. The hydrogenated product may be removed by known means such as distillation and/or chromatography.